Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 106

ESA - Functions of Engine EC U
STABLE IDLING CORRECTIO N
When the engine speed during idling has fluc-
tuated from the target idle speed, the Engine ECU
adjusts the ignition timing to stabilize the engine
speed .
The ECU is constantly calculating the average
engine speed . If the engine speed falls below
the target speed, the ECU advances the ignition
timing by a predetermined angle . If the engine
speed rises above the target speed, the ECU
retards the ignition timing by a predetermined
angle . The ignition timing angle is changed a
maximum of approximately ±5° by this
correction .
This correction is not executed when the engine
exceeds a predetermined speed .
O
f _
Difference from target idle speed
OHP 6 6
-RELEVANT SIGNALS
• Engine speed (NE )
• Throttle position (IDL)
• Vehicle speed (SPD )
REFERENCE
1 . In some engine models, the advance angl e
changes depending on whether the air
conditioner is on or off .
2 . In some engine models, this correction only
operates when the engine speed is below
the target engine speed .
EGR CORRECTIO N
When the EGR is operating and the IDL contact
is off, the ignition timing is advanced according
to the volume of the intake air and the engine
speed to improve drivability.
-RELEVANT SIGNAL S
• Intake manifold pressure ( PIM) or intake air
volume (VS, KS or VG )
• Engine speed (NE )
• Thro tt le position (IDL and PSW or VTA )
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